Apparatus permitting a thermal transformation, particularly for isomerization of pinene into dipentene



y 1, 1951 P. M. BOURDON 2,551,361

APPARATUS PERMITTING A THERMAL TRANSFORMATION PARTICULARLY FORISOMERIZATION OF PINENE INTO DIPENTENE Filed Feb. 8, 1949 [WE-Mm? Ham M1051 Baa/1W4 Patented May 1, 1951 APPARATUS PERMITTING'A TRANSFORMATION,PARTICULARLY FOR ISOMERIZATION INTO DIPENTENE Pierre Marcel Bourdon,Paris, France, assignor to Manufacture de Caoutchouc Michelin (Puise'ux,Bculanger et Cie), Clermont-Ferrand,

France .OF PINENE Application February 8, 1949, Serial No. 75,274

In France February 12,. v19418 3 Claims.

The invention has for object to provide an apparatus permitting thethermal transformation under pressure of one product into another. It isparticularly applicable for the continuous isomerisation of pinene intodipentene.

It has been known for some time that pinene can be isomerised intodipentene by heat in the liquid state under pressure.

This operation, carried out simply on a small scale, is complicated whenit is desired to deal with considerable quantities because of theslowness of the heating and cooling periods and especially because ofthe difficulty of effectually controlling the temperature, the heatdeveloped by the isomerisation tending to cause the temperature to risespontaneously.

The apparatus embodying the present invention overcomes thesedifliculties. It consists of an autoclave having an annular cylindricalspace for the downward circulation of the transformed liquid, a draw offdevice for the transformed liquid at the lower part of the said space, acoil pipe for "the upward circulation of liquid to be transformed and incourse of transformation the coil being wound in the annular spaceaforesaid, a chamber at the upper part of the said annular cylindricalspace into which the liquid in the coil discharges freely, and means formaintaining .the desired temperature and pressure in the said chamber.

In one example, the autoclave comprises two coaxial bells one within theother with a pipe coil disposed between them and open at its upperextremity, a heating device within the inner bell, a feed pipe for theproduct to be transformed connected with the lower end of the coil, ablow off pipe fitted with a cock and connected with the upper part ofthe outer bell for releasing therefrom any accumulated as or vapour, adraw-off orifice at the lower part of the outer bell for the transformedproduct, thermostatic means for maintaining the temperature at thedesired value, and means for maintaining a desired pressure within theapparatus.

Apparatus in accordance with the invention enables continuous andentirely automatic working to be achieved and requires only a very smallconsumption of calorific energy.

The annexed drawing discloses a diagrammatic section illustrating, byway of example, one apparatus embodying the invention and as applied forthe continuous isomerisation of pinene into dipentene.

Referring to the drawing, the body of the apparatus comprises twocylindrical steel bells I and 2 welded together coaxially' along the"rim I3. The outer bell I, as shown, is generally cylin drical, and hasa closed upper end. The inner hell 2 or core is similar in shape but isshorter and is of smaller diameter than the bell I.

The initial cold essence (pinene a) supplied by a pump, not shown,enters at 3 at the base of the autoclave and flows through the coil pipe4 wound helically in the annular space 5 between the two bells l and 2.This tube has an open upper end I2 communicating with the chamber Iiformed in the upper part of the bell I. The essence flowing upwards inthe coil 4 is heated by contact of the coil with the hot isomerisedessence (dipentene) which is in the space 5 and moves downwards incounter-flow'on the outside'of the coil 4. During this heating, thepine'ne is transformed into dipente'ne which es capes in cooledcondition through a discharge valve l situated at the" bottomof theouter bell I.

The outer bell I is provided with a jacket containing heat insulatingmaterial 8. The apparatus is heated electrically by a heating coil'orresistance-9 near the top of the inner bell or coil 2. A thermostaticregulatormaintains the temperature in thechamber I2 at about'250. At I9there is diagrammatically indicated'a thermometric device for actuatingthe thermostatic regulator.

The output of the apparatus is a function of its capacity. At thetemperature conditions above specified, the essence should remain abouttwo hours in the heated Zone. The useful capacity should therefore betwice the desired hourly output. It is possible to increase the outputof a given apparatus by elevating the temperature to 260 or even more,but then the yield of the operation is lowered by reason of a moreabundant formation of polymers.

It is advantageous to maintain in the autoclave a sufficiently strongover-pressure, 40 hectopizes for example, in order to keep in a liquidstate the water that may be contained in the essence treated. As shownin the drawing, a container I5 filled with a fluid under pressure isconnected to the autoclave through pipe I6 and gauge H. In all cases,the apparatus should comprise at the top a small blow-off cock II forthe escape of gases which may accumulate there.

In order to give a better understanding of the functioning of theapparatus, two examples of practical utilization of the autoclave willbe given.

EmampZeI An apparatus of three litres capacity conupper ends of saidmembers, a helical pipe coll extending lengthwise of said space andwound around said inner member, said coil having an open upper endcommunicating with said chamher and a lower end through which liquid canbe introduced for flow upwardly through said coil into said chamber andfrom the latter downthe lemon odour and is of the same density as theinitial essence but its rotatory power is practically nil. It iscomposed of 80% dipentene practically free from non-transformed pineneand 20% of polymers non-entrainable by water vapour.

Example 2 The same apparatus is fed in the same conditions with essenceof maritime pine having a rotatory power [a]589=29. The power requiredin continuous current is 125 watts. The rotatory power of the rawisomerised product is [al589=,10.5.". Theproportion of polymers is Thedifferences as compared with Example 1 arise from the presence, in theessence of maritime pine, of nopinene which is not modified by thetreatment.

Although the autoclave has been described as applied to theisomerisation of pinene, it is to be understood that the invention isnotlimited to that application but can be employed for any reactionrequiring a heating under pressure.

I claim:

1. An apparatus for thermal transformationof compounds, comprising afirst elongated hollow cylindrical member having opposite closed ends, ahollow cylindrical core in said first member and formingtherewith aclosed substantially annular space communicating at one end with anenlarged chamber between the ends of said hollow member and core, a pipecoil encircling the core and extending lengthwise thereof, said coilhaving an open end communicating with said chamber, means forintroducing liquid into the opposite end of said coil remote from saidchamber, meansfor discharging liquid at the end of said annularspaceremote from said chamber, and means within said hollow core to heatsaid chamber.

2. An apparatus for thermal transformation of compounds comprising anouter elongated hollow member having opposite upper and lower closedends, a smaller elongated hollow member within andspaced from the sidesand upper end of said outer member to form therewith a substantiallyannular elongated closed space communicating at its upper end with alarge chamber between the wardly through said space, means fordischarging liquid from the lower end of said space, and means withinsaid inner member for heating liquid in the upper end of said coil andsaid chamber.

3. An apparatus for thermal transformation of compounds comprising anouter elongated hollow member having opposite upper and lower closedends, a smaller elongated hollow member within and spaced from the sidesand upper end of said outer member to form therewith a substantiallyannular elongated closed space communicating at its upper end withalarge chamber between the upper ends of said members, a helical pipecoil extending lengthwise of said space and wound around said innermember, said coil having an upper open end communicating with saidchamber and a lower end through which liquid can be introduced for flowupwardly through said coil into said chamber and from the latterdownwardly through said space, means to discharge liquid from the lowerend of said space, means within said inner member for heating liquid inthe upper end of said coil and said chamber, an escape and blow offvalve at the upper end of said outer member to evacuate gasesaccumulated therein, thermostatic means responsive to the temperature ofsaid chamber to control said heating means and maintain a desiredtemperature in said chamber, and means to maintain a predeter minedsuperatmospheric pressure within said chamber and said annular space.

PIERRE MARCEL BOURBON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Date

